1. Field of the Invention
The present invention relates to using a mobile device with integrated motion sensing to evaluate golf swings and provide customized golf club fitting, specific golf product recommendations, and targeted golf-related marketing.
2. Description of the Related Art
Customized golf clubs “fitted” to the swing of a particular user have the advantage of enabling average players to significantly improve their scores by hitting the ball a longer distance and more accurately. With a custom fit driver for example, an average-to-intermediate player may hit the ball 10 to 20 yards farther, and will more accurately hit the fairway, instead of the rough or out of bounds, which in turn may lower their score by several strokes in a round. For advanced players, customized golf clubs are an essential component of competitive play, as most players have custom fit golf clubs and those that do not are at a disadvantage.
Hitting a golf ball long and straight is in principle easy but in practice is extremely difficult: The golfer has to generate maximum club head speed (swing speed) and has to hit the golf ball square at impact with the golf club head. The distance a golf ball flies in the air then rolls on the ground is determined by physics. For the driver, for example, various manufactures have shown that for 100 miles per hour (mph) club head speed the optimal drive distance is realized from a 150 mph ball velocity off the club face, an 11 to 13 degree launch angle at impact and a ball spin rate 2500 to 2900 revolutions per minute (rpm). Different golf clubs (irons, woods, etc.) each have optimal parameters to enable maximum ball distance derived from experiments.
For a particular golfer the important golf club variables for custom club fitting are the lie angle, shaft flex, and the loft or angle of the face of the golf club. Additional variables include the weight of the golf club and the weighting distribution (location of the center of mass in each case) of the both the golf club and golf club head. For example, a golfer with a low swing speed would benefit from a lighter and softer, more flexible, shaft. This is because the shaft acts like a spring with a natural resonance; hence the ideal is to match the resonance of the shaft with the swing speed of the golfer to maximize the club head speed. Furthermore, a lighter shaft is easier to swing faster. As another example, a golfer who consistently slices the ball (has the club head open at impact which makes the ball curve to the right), would benefit from golf clubs with club heads that are both angled a few degrees closed and weighted closer to the shaft so as to increase their angular velocity around the shaft, squaring the club to the ball at impact. Conversely, a golfer who consistently hooks the ball (has the club head closed at impact which makes the ball curve to the left), would benefit from golf clubs with club heads that are a few degrees open and are weighted farther from the shaft so as to decrease their angular velocity around the shaft, squaring the club to the ball at impact.
Several golf club manufacturers offer custom golf clubs. PING for example, color codes their golf clubs to the type of player, and Taylor Made has pioneered adjustable golf club heads that can be customized to a player via adjusting various screws and weights in the club head. The custom golf club fitting process ranges from rather primitive to very sophisticated.
In very basic club fitting for irons, for example, the fitter may tape the end of the club with masking tape and have the user make several swings hitting a ball into a net off a mat. As the club impacts the mat on the floor scuff-marks appear on the masking tape on the bottom of the club head at one end or the other. Scuff marks close to the shaft suggest that the player has a positive lie angle (is angling the far end of the club head up at impact), scuff marks away from the shaft suggest the player has a negative lie angle (is angling the far end of the club head down at impact). The club head is then bent in a vice using a bracket device to measure the angle of the club head, and the golfer repeats the process with new tape and the adjusted club until the scuff marks appear in the middle of the head—the club head is then approximately square at impact to the ball. All of the irons are then bent in a vice to the same lie angle and open or closed angle.
For the most basic fitting (which is typical in the average golf store) the shaft flex is selected based upon a subjective estimate of the golfer's ability. For example, a young and strong and/or expert golfer will be recommended a stiff shaft flex, a middle-aged high handicap golfer an intermediate flex, and a beginner, female, or older golfer a soft (more flexible) flex. The approximate cost for fitting golf clubs using this basic approach is several dollars per golf club, however the shaft selection often lacks any data to support the recommendation, and the masking tape scuff-mark approach for lie angle is fraught with potential errors, so that golf clubs fitted using this approach are often far from optimal.
The most sophisticated golf club fitting utilizes a high-speed digital camera and computer system, called a launch monitor system, to actually measure the club head speed, the speed of the golf ball and the flight angle of the golf ball following impact (the launch angle), the club lie angle pre and post impact, and the ball spin rate. The club fitter's goal is to create custom golf clubs so that an individual golfer creates, as closely as possible, the optimal club head speed, ball speed, launch angle, and ball spin rate for each specific club.
These systems are expensive and are often available only in a few high-end golf shops. The club fitting process involves the golfer taking many swings hitting a ball into a net or on a driving range with the launch monitor focused at the impact area of the club head with the ball. Additional data includes the measured flex of the existing golf club shaft for comparison. The shaft flex may be measured by clamping the shaft at the grip, then pulling back the head and letting the club oscillate—the frequency of oscillation is the resonance of the shaft. The club fitter takes the launch monitor data and, via a table of club specification data, looks-up the optimal club for the measured swing metrics. The table is often stored in a database or spreadsheet on the same personal computer the launch monitor software is loaded onto.
As an example for fitting the driver, a golfer swings clubs with different heads and shafts and the fitter works to optimize their carry, roll distance, and accuracy based upon the launch monitor data—the improvement in performances is measured relative to their original not-fitted golf club. The results are new clubs accurately fitted to the specific golfer; however the cost for fitting clubs using this approach is several hundred dollars for each golf club. Hence, these systems are currently available only to the affluent and to professional golfers.
The prior art includes a few patent and patent publications disclosing the use of gyroscopes and accelerometers for analyzing golf swings. However, these methods require customized attachments inserted into, or attached to, a golf club. For example, Published Patent Application No. 2005/0054457 to Eyestone discloses a method and system for golf swinging analysis and training that employs a device inserted into the distal end of a golf club. The device includes a gyroscope and an accelerometer and can wirelessly communicate with a personal computer to capture golf swing data while the user swings the golf club. Similarly, WIPO Publication No. WO2011/085494 to Hashimoto et al. discloses such a device with a gyroscope and accelerometer that attaches to the outside of a golf club.
Furthermore, PING, Inc. has developed a putting analysis system wherein users hit physical balls while putting, and motion sensors in a mobile phone clipped onto the physical golf club provide data used by an application to analyze the putt, and to compare results to that of professional golfers. These data can be used to custom fit a golf putter. However, such prior art systems and methods require impact with a physical ball, and/or use of, or attachment to, sports equipment.